Variable Neutral Density filters - anyone here ever used one?

Discussion in 'Miscellaneous Equipment' started by TheFlyingCamera, Sep 17, 2013.

  1. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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  2. Ian Grant

    Ian Grant Subscriber

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    Sounds like a double polarising filter.

    Ian
     
  3. Truzi

    Truzi Subscriber

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    It is similar to having two polarizing filters and rotating one. Alternately, look at an LCD monitor or LCD TV through the lens of a pair of polarized sunglasses, then start to rotate the lens - same principle. You could also look at the screen with a camera's polarizing filter. (An LCD screen has a polarized filter. When the liquid crystals line-up in a certain orientation to the filter, they block the light, causing the image you see on your LCD. This works with any LCD display, even watches.)

    I bought a cheap variable ND filter to tape on the front of a pinhole camera I made from a cigarillo box, wanting long exposures. I first put it on my 35mm while pointing at a flat light source, rotated the lens, and watched the in-camera meter. This way I was able to get an _approximate_ idea of how much light-reduction I had at each marking on the filter-ring.

    Seeing that I'm new to pinhole cameras, I can't really comment on how well it worked. It gave me what I wanted, though. I have used it on my 35mm a few times and it seemed okay, but I'm not the best photographer, so what is acceptable to me may not be to others.

    Those others can tell you if a variable ND filter will degrade your photos compared to a "static" ND filter.
     
  4. AgX

    AgX Member

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    No answer to the question, but buying another polarizer (preferably of the same qality as the the first one) will get you there too, though slightly a bit more clumsy as both filter are able to rotate, unless one is locked somehow.
     
  5. MattKing

    MattKing Subscriber

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    I was given a no-name 77mm version of same, and have experimented with it a little bit. It isn't fully "calibrated" yet, so I don't have any good examples to show.

    They are available at a number of different price points, from incredibly cheap to really expensive.

    The cheap ones are vulnerable to being uneven in their effect.
     
  6. Dr Croubie

    Dr Croubie Member

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    Just a word of caution about buying a cheap one and/or just sticking two CPLs together back-to-back (or is it front-to-front?). At very-low and very-high filter factors, you can get a colour cast, I've tried building my own and managed to get it at a point of the whole shot going rather green or rather purple. Even with digital that's useless, I'd hate to try to remove a colour cast from film. Also, you can get a cross-hatching effect in certain circumstances.

    I'm all for saving money on a lot of things (and very often do), but with vari-NDs more than anything you really do get what you pay for. I've never heard a bad word said about Singh-Ray or Heliopans (except the price, see here for a simple comparison, Singh-Rays and Heliopans are 10x the price of the cheapest Vivitar/Polaroids).
     
  7. AgX

    AgX Member

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    I know of polarizers that got a colour cast. But that colour cast only at low and high densities you describe puzzles me.
     
  8. cliveh

    cliveh Subscriber

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    A photographer once showed me some wonderful 10" X 8" colour transparencies taken with a polarising filter and rule number one, don't buy a cheap version. You get what you pay for.
     
  9. mesantacruz

    mesantacruz Subscriber

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    I for one advise against them... I myself bought a cheap one off of ebay in order to increase my exposure by the most i could. The reason i went for one of these is, i ended up reading that even high end ones tend to give you that 'cross' (cross hatch?) look, although some have a stopping mechanism so that you can't fully rotate them (as the cheap ones do) and so you don't ever notice when it starts or stops. The cheap ones do degrade the image noticeably, and i fear i'm sure the expensive ones do as well, perhaps to a lesser extent.

    I recommend only using 'single density' nd filters as they are many times better.


    I ended up getting (again from ebay, reading reviews this time) an equivalent 10 stop filter, which actually does the job. For black and white it is great! Unfortunately, doing my exposures for several minutes i don't calculate reciprocity failure very well, nevertheless, it has been very fun to use it, especially the times it did work. I went for the 77mm as it fits my mamiya lenses as well.
    If you are to use one with color i would be careful with color casts (as a user of dig*tal i can fix this specific filter with large amounts of white balance, but for film, i can't imagine the work it would take).
     
  10. polyglot

    polyglot Member

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    I've been looking at these recently - there are some Polaroid branded ones going cheap on eBay. I've not tried one though and I think I'll just buy an Haida ND3.0-II (1000x) for long exposures.

    Putting a pair of polarisers front-to-front is HORRIBLE, even ignoring the mechanical craziness needed with reversing rings and stuff. Once you get past about 6 stops, you get very dense and uneven colour casts with funny patterns in them. I'm not sure, but I suspect the problem is the presence of the quarter-wave plate on the input (what was the back of a circular polariser) side. Their effect, being to introduce a 90-degree phase lag in one axis with respect to the other and thereby convert linear to circular polarisation, is strongly wavelength-dependent. A commercial vari-ND would have to be far, far better than combining polarisers manually, even if that's how they work internally.
     
  11. jeffreyg

    jeffreyg Subscriber

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    The filter you linked to is a 52mm filter so having one would depend on the lens. Personally, although I have a couple of ND filters they fit four of my Hasselblad lenses, I don't use them very often. B+W has seven ND filters with densities from 0,3 to 6,0 with a range of 1 to 20 stops. Stacking polarizers as mentioned might cause vignetting as well as the other issues mentioned.

    http://www.jeffreyglasser.com/
     
  12. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    I'm not looking to stack polarizers. I was just inquiring about these specific types of variable neutral-density filters. Sounds like they have issues at any price point I'd be willing to spend. I was just looking to see if there was a way around having to carry multiple filters, and to avoid using my Lee gelatin filters with my Rolleiflex.
     
  13. mesantacruz

    mesantacruz Subscriber

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    That's good, i didn't want to steer anyone away from experimenting, but stacking polarizers was a def no go.. and from our experiences, neither are vari-nd filters... and sadly that leaves one with single stop nd filters. I recommend you get a 2 stop. which is good and another stronger nd filter (not recommended for color, even lee big stopper has a disclaimer on it's website) for several minute long exposures which are fun. just my 2 cents.
     
  14. kintatsu

    kintatsu Member

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    I have one. It's a Hama 2-400 vario ND filter that I have. It allowsw one to vary the amount of optical density added. I provides from 1 to 8 (or 10?) stops of density.

    I haven't used it, nor have I had the need! I'm still planning to, so who knows.